Radiography using ultra-short laser-produced proton beams is a development of traditional proton radiography. According to the characteristic of laser-produced proton beam, using FLUKA Monte-Carlo program, the quantitative simulation of proton radiography is studied. From the simulation of three typical cases （half-plane target and ladder target, hohlraum with a plastic ball in it,and detection of magnetic field with mesh method）, the main physical factors that effect the proton radiography are discussed. The advantage of radiography of laser-produced protons, such as high sensitivity to boundary, high spatial resolution, and high sensitivity to magnetic field, is demonstrated.